A codec listening test is a

scientific Science is a systematic endeavor that builds and organizes knowledge in the form of testable explanations and predictions about the universe. Science may be as old as the human species, and some of the earliest archeological evidence ...

study Study or studies may refer to: General * Education **Higher education * Clinical trial * Experiment * Observational study * Research * Study skills, abilities and approaches applied to learning Other * Study (art), a drawing or series of drawin ...

designed to compare two or more

lossy In information technology, lossy compression or irreversible compression is the class of data compression methods that uses inexact approximations and partial data discarding to represent the content. These techniques are used to reduce data size ...

audio Audio most commonly refers to sound, as it is transmitted in signal form. It may also refer to: Sound *Audio signal, an electrical representation of sound *Audio frequency, a frequency in the audio spectrum * Digital audio, representation of soun ...

codec A codec is a device or computer program that encodes or decodes a data stream or signal. ''Codec'' is a portmanteau of coder/decoder. In electronic communications, an endec is a device that acts as both an encoder and a decoder on a signal or ...

s, usually with respect to perceived

fidelity Fidelity is the quality of faithfulness or loyalty. Its original meaning regarded duty in a broader sense than the related concept of ''fealty''. Both derive from the Latin word ''fidēlis'', meaning "faithful or loyal". In the City of London ...

or compression efficiency. Most tests take the form of a

double-blind In a blind or blinded experiment, information which may influence the participants of the experiment is withheld until after the experiment is complete. Good blinding can reduce or eliminate experimental biases that arise from a participants' expec ...

comparison. Commonly used methods are known as " ABX" or "ABC/HR" or " MUSHRA". There are various software packages available for individuals to perform this type of testing themselves with minimal assistance.

Testing methods

ABX test

In an ABX test, the listener has to identify an unknown sample X as being A or B, with A (usually the original) and B (usually the encoded version) available for reference. The outcome of a test must be statistically significant. This setup ensures that the listener is not biased by his/her expectations, and that the outcome is not likely to be the result of chance. If sample X cannot be determined reliably with a low

p-value In null-hypothesis significance testing, the ''p''-value is the probability of obtaining test results at least as extreme as the result actually observed, under the assumption that the null hypothesis is correct. A very small ''p''-value means ...

in a predetermined number of trials, then the

null hypothesis In scientific research, the null hypothesis (often denoted ''H''0) is the claim that no difference or relationship exists between two sets of data or variables being analyzed. The null hypothesis is that any experimentally observed difference is d ...

cannot be rejected and it cannot be proved that there is a perceptible difference between samples A and B. This usually indicates that the encoded version will actually be '' transparent'' to the listener.

ABC/HR test

In an ABC/HR test, C is the original which is always available for reference. A and B are the original and the encoded version in randomized order. The listener must first distinguish the encoded version from the original (which is the Hidden Reference that the "HR" in ABC/HR stands for), prior to assigning a score as a subjective judgment of the quality. Different encoded versions can be compared against each other using these scores.

MUSHRA

In MUSHRA (MUltiple Stimuli with Hidden Reference and Anchor), the listener is presented with the reference (labeled as such), a certain number of test samples, a hidden version of the reference and one or more anchors. The purpose of the anchor(s) is to make the scale be closer to an "absolute scale", making sure that minor artifacts are not rated as having very bad quality.

Results

Many double-blind music listening tests have been carried out. The following table lists the results of several listening tests that have been published online. To obtain meaningful results, listening tests must compare codecs' performance at similar or identical bitrates, since the audio quality produced by any

encoder will be trivially improved by increasing the bitrate. If listeners cannot consistently distinguish a lossy encoder's output from the uncompressed original audio, then it may be concluded that the codec has achieved

transparency Transparency, transparence or transparent most often refer to: * Transparency (optics), the physical property of allowing the transmission of light through a material They may also refer to: Literal uses * Transparency (photography), a still ...

. Popular formats compared in these tests include

MP3 MP3 (formally MPEG-1 Audio Layer III or MPEG-2 Audio Layer III) is a coding format for digital audio developed largely by the Fraunhofer Society in Germany, with support from other digital scientists in the United States and elsewhere. Orig ...

AAC AAC may refer to: Aviation * Advanced Aircraft, a company from Carlsbad, California * Alaskan Air Command, a radar network * American Aeronautical Corporation, a company from Port Washington, New York * American Aviation, a company from Cleveland, ...

(and

extensions Extension, extend or extended may refer to: Mathematics Logic or set theory * Axiom of extensionality * Extensible cardinal * Extension (model theory) * Extension (predicate logic), the set of tuples of values that satisfy the predicate * Ext ...

Vorbis Vorbis is a free and open-source software project headed by the Xiph.Org Foundation. The project produces an audio coding format and software reference encoder/decoder (codec) for lossy audio compression. Vorbis is most commonly used in con ...

Musepack Musepack or MPC is an open source lossy audio codec, specifically optimized for transparent compression of stereo audio at bitrates of 160–180 (manual set allows bitrates up to 320) kbit/s. It was formerly known as MPEGplus, MPEG+ or MP+. ...

, and WMA. The RealAudio Gecko, ATRAC3, QDesign, and

mp3PRO mp3PRO is an unmaintained proprietary audio compression codec that combines the MP3 audio format with the spectral band replication (SBR) compression method. At the time it was developed it could reduce the size of a stereo MP3 by as much as 50% w ...

formats appear in some tests, despite much lower adoption . Many encoder and decoder implementations (both proprietary and

open source Open source is source code that is made freely available for possible modification and redistribution. Products include permission to use the source code, design documents, or content of the product. The open-source model is a decentralized sof ...

) exist for some formats, such as

, which is the oldest and best-known format still in widespread use today. {, class="wikitable sortable" , - , style="text-align: center;" ! style = "font-size: 84%" , Source ! style = "font-size: 84%" , Dates ! style = "font-size: 84%" , Formats ! style = "font-size: 84%" , Bitrate (kbit/s) ! style="width:24em;" , Codecs ! style = "font-size: 84%" class=unsortable , Musical genres ! style = "font-size: 84%" , Samples ! style = "font-size: 84%" , Listeners ! style = "font-size: 92%" , Best Result ! style="width:19em;" class=unsortable , Comments , - , style="text-align: center;"
ff123
, style = "font-size: 84%" , 2001 , multiple , ~128 , style = "font-size: 92%" , * MP3: Lame 3.89beta --abr 134 -h --nspsytune—athtype 2 --lowpass 16—ns-bass -8 * MP3: Xing within AudioCatalyst 2.1 128 kbit/s, high frequency mode disabled, simple stereo disabled * AAC: Liquifier Pro 5.0.0 Beta 2, Build 24 streaming 128, equalization disabled, dynamics disabled, dual mono encoding disabled, audio bandwidth overridden by the program, set at 17995 Hz * MPC: mppenc.exe version 1.7.9c -radio -ltq_gain 10 -tmn 12 -nmt 4.8 * WMAv8: Windows Media Player 7.1 (version 7.01.00.3055); Wmadmoe.dll version 8.0.0.0371 128 kbit/s * Ogg Vorbis: Oggdrop RC2 for Windows 32 128 kbit/s , , 1 , 16 , style = "font-size: 92%" ,

and

, , - , style="text-align: center;"
ff123
, style = "font-size: 84%" , 2001 October - 2002 January , multiple , ~128 , style = "font-size: 92%" , * MP3: Lame 3.89beta --abr 134 -h --nspsytune—athtype 2 --ns-bass -8 * MP3: Xing within AudioCatalyst 2.1 128 kbit/s, high frequency mode disabled, simple stereo disabled * AAC: Liquifier Pro 5.0.0 Beta 2, Build 24 streaming 128, equalization disabled, dynamics disabled, dual mono encoding disabled, audio bandwidth overridden by the program, set at 17995 Hz * MPC: mppenc.exe version 1.7.9c -radio -ltq_gain 10 -tmn 12 -nmt 4.8 * WMAv8: Windows Media Player 7.1 (version 7.01.00.3055); Wmadmoe.dll version 8.0.0.0371 128 kbit/s * Vorbis: **Oggdrop pre-RC3 for Windows 32; from CVS (10/26/01) 128 kbit/s , style = "font-size: 84%" , Various , 3 , 25-28 , style = "font-size: 92%" ,

, , - , style="text-align: center;"
ff123
, style = "font-size: 84%" , 2002 July , multiple , ~64 , style = "font-size: 92%" , * Ogg Vorbis 1.0 -b 64—managed * Ogg Vorbis 1.0 -q 0 * MMJB 7.2 mp3PRO 64 * WMA8 at 64 kbit/s (using WMP 7.1 to encode) * QuickTime 6.0 MPEG-4 AAC Low complexity at 64 kbit/s , style = "font-size: 84%" , Various , 12 , 24-41 , style = "font-size: 92%" ,

, style = "font-size: 84%" , Both Vorbis variants were a close second. , - , style="text-align: center;"
Roberto Amorim
, style = "font-size: 84%" , 2003 June ,

, 128 CBR , style = "font-size: 92%" , * Psytel AAC-enc 2.15 -br 128 * Ahead/Nero 5.5.10.35 128 kbit/s CBR, high quality * Sorenson Squeeze 3.5 (FhG Pro) 128 kbit/s * Apple QuickTime 6.3 (Apple/Dolby) 128 kbit/s high quality * FAAC 1.17b -a 64 (64 kbit/s/channel, ABR) , style = "font-size: 84%" , Various , 10 , 11-18 , style = "font-size: 92%" ,

QuickTime QuickTime is an extensible multimedia framework developed by Apple Inc., capable of handling various formats of digital video, picture, sound, panoramic images, and interactivity. Created in 1991, the latest Mac version, QuickTime X, is a ...

, , - , style="text-align: center;"
Roberto Amorim
, style = "font-size: 84%" , 2003 July , multiple , ~128 , style = "font-size: 92%" , * Apple QuickTime 6.3 MP4 encoder 128 kbit/s high quality * LAME MP3 Encoder 3.90.3 --alt-preset 128 * Musepack 1.14 --quality 4 --xlevel * Ogg Vorbis post-1.0 CVS -q 4.25 * Windows Media Audio v9 PRO bitrate-managed 2-pass VBR 128 kbit/s , style = "font-size: 84%" , Various , 12 , 14-24 , style = "font-size: 92%" ,

, style = "font-size: 84%" , AAC, WMA, and

tied for close second , - , style="text-align: center;"
Roberto Amorim
, style = "font-size: 84%" , 2003 September , multiple , ~64 , style = "font-size: 92%" , * Ahead/Nero 6.0.0.15 HE AAC VBR profile Streaming :: Medium, high quality * Ogg Vorbis post-1.0 CVS -q 0 * mp3PRO (from Adobe Audition 1.0) VBR quality 40, Current Codec, allow M/S and IS, allow narrowing, no CRC * Real Audio Gecko (from Real Producer 9.0.1) 64 kbit/s * Windows Media Audio v9 VBR quality 50 * QuickTime 6.3 AAC LC 64 kbit/s, Best Quality , style = "font-size: 84%" , Various , 12 , 30-43 , style = "font-size: 92%" , Nero
HE-AAC , style = "font-size: 84%" , This test showed that listeners preferred 128 kbit/s MP3 audio encoded by

LAME Lame or LAME may refer to: Music * "Lame" (song) by Unwritten Law * ''Lame'' (album) by Iame People * Ibrahim Lame (born 1953), Nigerian educator and politician * Jennifer Lame (), American film editor * Quintín Lame (1880–1967), Colombia ...

to ''all'' the tested codecs at 64 kbit/s, with greater than 99% confidence: "No codec delivers the marketing plot icof same quality as MP3 at half the bitrates." , - , style="text-align: center;"
Roberto Amorim
, style = "font-size: 84%" , 2004 January ,

, ~128 , style = "font-size: 92%" , * LAME encoder 3.95 --preset 128 * FhG MP3 encoder from Adobe Audition 1.0 VBR quality 40, "Current - Best" codec. * Apple iTunes 4.2 MP3 112 kbit/s VBR, Highest quality, joint stereo, smart encoding * GOGO-no-coda 3.12 -b 128 -a -q 0 * Audioactive Encoder 2.04 128 kbit/s High Quality * Xing MP3 Encoder 1.5 VBR quality normal , style = "font-size: 84%" , Various , 12 , 11-22 , style = "font-size: 92%" ,

, style = "font-size: 84%" , The author noted that the results may have been affected by the use of an outdated version of the Xing encoder and non-optimal settings for ITunes. , - , style="text-align: center;"
Roberto Amorim
, style = "font-size: 84%" , 2004 February ,

, ~128 , style = "font-size: 92%" , * Ahead/Nero AAC-enc v 2.6.2.0 -internet profile, high quality, LC * Apple iTunes 4.2 (Apple/QuickTime) 128 kbit/s * Compaact! 1.2beta3 (zPlane/HHI) VBR 5, high quality, LC * FAAC 1.23.5 -q 115 * Real Producer 10 beta (CodingTechnologies) 128 kbit/s , Various , 12 , 19-29 , style = "font-size: 92%" , iTunes , style = "font-size: 84%" , Open-source FAAC codec improved greatly since previous test , - , style="text-align: center;"
Roberto Amorim
, style = "font-size: 84%" , 2004 May , multiple , ~128 , style = "font-size: 92%" , * LAME encoder 3.96 -V5—athaa-sensitivity 1 * Apple iTunes 4.2 128 kbit/s AAC * Ogg Vorbis aoTuV tuning b2 -q 4.35 * Musepack 1.14b --quality 4.15—xlevel * Sony Atrac3 132 kbit/s * Microsoft WMA9 Std Bitrate VBR 128 kbit/s , style = "font-size: 84%" , Various , 18 , 12-27 , style = "font-size: 92%" , aoTuV (Vorbis) and

, , - , style="text-align: center;"
Roberto Amorim
, style = "font-size: 84%" , 2004 June , multiple , 32 CBR , style = "font-size: 92%" , * LAME encoder 3.96 -b 32 * Nero Ahead HE AAC+PS 32 kbit/s CBR High Quality * Ogg Vorbis post-1.0.1CVS --managed -b 32 resampled with SSRC * Real Audio 32 kbit/s stereo music codec in Helix Producer 10 * QDesign Music Codec 2 Pro 32 kbit/s at 32 kHz, Quality mode * Microsoft WMA9 Std 32 kbit/s at 32 kHz * mp3PRO 32 kbit/s at 32 kHz, in Adobe Audition 1.5 , style = "font-size: 84%" , Various , 18 , 47-77 , style = "font-size: 92%" , Nero
HE-AAC , , - , style="text-align: center;" , style = "font-size: 84%"
HydrogenAudio user "guruboolez"
, style = "font-size: 84%" , 2004 July , multiple , ~175 , style = "font-size: 92%" , * MPC: musepack -standard * MP3: LAME 3.97 alpha -V 3; -V 2 * Ogg Vorbis: megamix -q 6,00; -q 6,99; -q 5,50 , Classical , 18 , 1 , style = "font-size: 92%" ,

, , - , style="text-align: center;" , style = "font-size: 84%"
HydrogenAudio user "guruboolez"
, style = "font-size: 84%" , 2005 August , multiple , ~180 , style = "font-size: 92%" , * AAC: Faac 1.24.1. Release date: end 2004 (?). Setting: -q175 * AAC: Nero Digital aacenc32 v.3.2.0.15. Release date: June 2005. Setting: -streaming (high/default encoder). * MP3: LAME 3.97 alpha 11. Release date: July 2005. Setting: -V2—vbr-new * MPC: mppenc 1.15v. Release date: march 2005. Setting: --quality 5 * Ogg Vorbis: aoTuV beta 4 based on 1.1.1. Release date: July 2005. Setting: -q6,00 , Classical , 18 , 1 , style = "font-size: 92%" , aoTuV (Vorbis) , style = "font-size: 84%" , The author reflects on substantial improvements in Vorbis encoding since his previous test (above): "Vorbis is now –thanks to Aoyumi reator of aoTuV�� an excellent audio format for 180 kbit/s encodings (and classical music)." , - , style="text-align: center;" , style = "font-size: 84%"
gURuBoOleZZ
, style = "font-size: 84%" , 2005 August , multiple , ~96 , style = "font-size: 92%" , * AAC-LC: iTunes 4.9 / QuickTime 7.02 CBR 96 * MP3: LAME 3.97 alpha 11 --abr 99 * MPC: mppenc 1.14 --xlevel—quality 3 (or—thumb) * Ogg Vorbis: aoTuV / LANCER beta 4 based on SVN 1.1.1 -q2,00 * WMA Standard: WMA 9.1 CBR 96 ,

Classic A classic is an outstanding example of a particular style; something of lasting worth or with a timeless quality; of the first or highest quality, class, or rank – something that exemplifies its class. The word can be an adjective (a '' ...

, various , style = "font-size: 84%" , 150 classical, 35 various , 1 , style = "font-size: 92%" , aoTuV and

tied (classical), aoTuV (various) , style = "font-size: 84%" , The author selected each participating encoder by pitting multiple encoders against one another in an initial "Darwinian phase." For example, LAME was chosen as the representative MP3 encoder because it clearly outperformed four other MP3 encoders on a subset of the full sample corpus. , - , style="text-align: center;" , style = "font-size: 84%"
Sebastian Mares
, style = "font-size: 84%" , 2005 December , multiple , ~140 (nominal 128) , style = "font-size: 92%" , * Nero AAC 3.1.0.2 VBR/Stereo - Streaming, 100-120 kbit/s C AAC* iTunes AAC 6.0.1.3 128 kbit/s, VBR * LAME 3.97 Beta 2 -V5—vbr-new * Ogg Vorbis AoTuV 4.51 Beta -q 4.25 * WMA Professional 9.1 Quality-Based VBR, Q50 * Shine 0.1.4 (Low Anchor) -b 128 , style = "font-size: 84%" , Various , 18 , 18-30 , style = "font-size: 92%" , 4-way tie (all except Shine) , style = "font-size: 84%" , "I think this test shows that with the current encoders, the quality at 128 kbit/s is very good... It's time to move to bitrates like 96 kbit/s or even lower (64 kbit/s)." , - , style="text-align: center;" , style = "font-size: 84%"
Mp3-tech.org
, style = "font-size: 84%" , 2006 March , AAC , 48 , style = "font-size: 92%" , * 3gpp 6.3.0 48kbit/s CBR * Coding Technologies - Winamp 5.2 beta 393 48kbit/s CBR HE-AAC * Coding Technologies - Winamp 5.2 beta 393 48kbit/s CBR HEv2-AAC * Nero Digital 4.9.9.95 48kbit/s ABR HE-AAC * Nero Digital 4.9.9.96 48kbit/s ABR HEv2-AAC * iTunes 6.0.2 (Low Anchor) 48kbit/s CBR * LAME 3.97b2 (High Anchor) -V5 , style = "font-size: 84%" , Various , 18 , 10-20 , style = "font-size: 92%" , 5-way tie
(all except anchors) , style = "font-size: 84%" , "... it seems that overall, plain HE-AAC might be better than HE-AAC v2 at this bitrate, but a lot more samples would be needed to be able to draw definitive conclusions regarding this. , - , style="text-align: center;" , style = "font-size: 84%"

, style = "font-size: 84%" , 2006 November , multiple , ~48 , style = "font-size: 92%" , * Ogg Vorbis AoTuV 5 Beta -q -1 * WMA Professional 10 1-pass CBR, 48 kbit/s * Nero HE-AAC May 26, 2006 -q 0.2 * WMA Standard 9.2 Quality-Based VBR, Q10 * iTunes AAC 7.0.2.16 48 kbit/s, CBR , style = "font-size: 84%" , Various , 20 , 22-34 , style = "font-size: 92%" , Nero
HE-AAC , style = "font-size: 84%" , WMA Professional and aoTuV tied for second , - , style="text-align: center;" , style = "font-size: 84%"
Sebastian Mares
, style = "font-size: 84%" , 2007 July , multiple , ~64 , style = "font-size: 92%" , * Ogg Vorbis AoTuV 5 Beta -q 0 * WMA Professional 10 1-pass CBR, 64 kbit/s * Nero HE-AAC Jul 20 2007 -q 0.24 , style = "font-size: 84%" , Various , 18 , 21-33 , style = "font-size: 92%" ,

Nero Digital Nero Digital is a brand name applied to a suite of MPEG-4-compatible video and audio compression codecs developed by Nero AG of Germany and Ateme of France. The audio codecs are integrated into the ''Nero Digital Audio+'' audio encoding tool for ...

and WMA Professional , , - , style="text-align: center;" , style = "font-size: 84%"
Sebastian Mares
, style = "font-size: 84%" , 2008 October , MP3 , ~128 , style="font-size: 92%" , * LAME 3.98.2 -V5.7 * LAME 3.97 -V5—vbr-new * iTunes 8.0.1.11 112 kbit/s, VBR, highest quality, joint stereo, smart encoding, filter below 10 Hz * Fraunhofer IIS mp3surround CL encoder v1.5 -br 0 -m 4 -q 1 -vbri -ofl * Helix v5.1 2005.08.09 -X2 -U2 -V60 * l3enc 0.99a (Low Anchor) -br 128000 -mod 1 , style = "font-size: 84%" , Various , 14 , 26-39 , style = "font-size: 92%" , 5-way tie
(all except L3enc) , style = "font-size: 84%" , "The quality at 128 kbps is very good and MP3 encoders improved a lot since the last test." Also notes that Fraunhofer and Helix codecs are several times faster at encoding than LAME, although virtually identical in terms of perceived audio quality. , - , style="text-align: center;" , style = "font-size: 84%"
HydrogenAudio user IgorC (March/April 2011)
, style = "font-size: 84%" , 2011 March , multiple , ~64 , style = "font-size: 92%" , * Ogg Vorbis AoTuV 6.02 Beta -q 0.1 * Apple HE-AAC constrained VBR, high quality, 64 kbit/s *

CELT The Celts (, see pronunciation for different usages) or Celtic peoples () are. "CELTS location: Greater Europe time period: Second millennium B.C.E. to present ancestry: Celtic a collection of Indo-European peoples. "The Celts, an ancien ...

complexity 10, VBR 67.5 kbit/s * Nero HE-AAC -q 0.245 , style = "font-size: 84%" , Various , 30 , 25-13 , style="font-size:92%" , CELT / Opus , style = "font-size: 84%" , I
results
CELT is referred to as

Opus ''Opus'' (pl. ''opera'') is a Latin word meaning " work". Italian equivalents are ''opera'' (singular) and ''opere'' (pl.). Opus or OPUS may refer to: Arts and entertainment Music * Opus number, (abbr. Op.) specifying order of (usually) publicati ...

, its name when later standardized. , - , style="text-align: center;" , style = "font-size: 84%"
HydrogenAudio user IgorC (July - August 2011)
, style = "font-size: 84%" , 2011 July/August , LC-AAC , ~96 , style = "font-size: 92%" , * Nero 1.5.4.0 -q 0.345 * Apple QuickTime 7.6.9 true VBR, high quality, 96 kbit/s * Apple QuickTime 7.6.9 constrained VBR, high quality, 96 kbit/s * Fraunhofer IIS (via Winamp 5.62) VBR 3 * Coding Technologies (via Winamp 5.61) CBR 100 kbps , style = "font-size: 84%" , Various , 20 , 25 , style = "font-size: 92%" , Apple QuickTime , , - , style="text-align: center;" , style = "font-size: 84%"

, style = "font-size: 84%" , 2013 May , MP3 , ~224 , style = "font-size: 92%" , * Lame3100i -V2+ * LAME 3.99.5 -V1 * LAME 3.98.4 -q 0 -b 224 * Helix v5.1 -X2 -U2 -V146 * BladeEnc (Low Anchor) -quit -nocfg -224 , style = "font-size: 84%" , Various , 25 , 1 , style = "font-size: 92%" , 4-way tie
(all except BladeEnc
low anchor) , style = "font-size: 84%" , Most impairment grades rated between 4 (perceptible but not annoying) and 5 (imperceptible). Both speech samples transparent (p<0.02) except for the low anchor. , - , style="text-align: center;" , style = "font-size: 84%"
HydrogenAudio user Kamedo2 (July/September 2014)
, style = "font-size: 84%" , 2014 July - September , multiple , ~96 , style = "font-size: 92%" , * AAC Apple QuickTime iTunes 11.2.2 (qaac 2.4.1) constrained VBR, high quality, 96 kbit/s * Opus 1.1 VBR, 96 kbit/s * Ogg Vorbis aoTuV Beta6.03 -q 2.2 (~96 kbps) * MP3 LAME 3.99.5 VBR, -V 5 (~130 kbps, a well-known comparison but at higher bitrate) * AAC FAAC v1.28 (Mid-low Anchor) -b 96 * AAC FAAC v1.28 (Low Anchor) -q 30 (~52 kbps) , style = "font-size: 84%" , Various , 40 , 33 , style = "font-size: 92%" ,

, style = "font-size: 84%" , I
results
Opus is clear winner, Apple AAC is second, Ogg Vorbis and higher-bitrate LAME MP3 are statistically tied in joint third place. FAAC, known to be inferior in advance, was used to discard bad results and as quality scale anchor. , - , style="text-align: center;" , style = "font-size: 84%", Cunningham and McGregor , style = "font-size: 84%" , 2019 February , multiple , 192 - 1411 , style = "font-size: 92%" , * Uncompressed WAV * MP3 CBR 192 kbps * AAC 192 kbps CBR * ACER low quality ~1023 kbps VBR * ACER medium quality ~1130 kbps VBR * ACER high quality ~1233 kbps VBR , style = "font-size: 84%" , Pop , 10 , 100 , style = "font-size: 92%" , 5-way tie (WAV, MP3, AAC, ACER HQ, ACER MQ) , style = "font-size: 84%" , Participants reported no perceived differences between the uncompressed, MP3, AAC, ACER high quality, and ACER medium quality compressed audio in terms of noise and distortions but that the ACER low quality format was perceived as being of lower quality. However, in terms of participants’ perceptions of the stereo field, all formats under test performed as well as each other, with no statistically significant differences.{{cite journal , last1=Cunningham , first1=Stuart , last2=McGregor , first2=Iain , title=Subjective Evaluation of Music Compressed with the ACER Codec Compared to AAC, MP3, and Uncompressed PCM , journal=International Journal of Digital Multimedia Broadcasting , volume=2019 , pages=1–16 , date=2019 , language=en, doi=10.1155/2019/8265301 , doi-access=free CC-BY icon

Material was copied from this source, which is available under
Creative Commons Attribution 4.0 International License
, - , style="text-align: center;" ! style = "font-size: 84%" , Source ! style = "font-size: 84%" , Dates ! style = "font-size: 84%" , Formats ! style = "font-size: 84%" , Bitrate (kbit/s) ! Codecs ! style = "font-size: 84%" , Musical genres ! style = "font-size: 84%" , Samples ! style = "font-size: 84%" , Listeners ! style = "font-size: 92%" , Best Result ! Comments

References

External links

Hydrogenaudio
- Community

audiophile An audiophile is a person who is enthusiastic about high-fidelity sound reproduction. An audiophile seeks to reproduce the sound of a piece of recorded music or a live musical performance, typically inside closed headphones, In-ear monitors, open ...

site, host of most non-commercial ABX testing
SoundExpert
Continuous blind listening tests of codecs over the internet Digital audio